B_4C/TiB_2复相陶瓷硬度压痕的尺寸效应  

Indentation Size Effect for the Hardness of B_4C/TiB_2 Ceramics

作　　者：郭伟明[1] 谭大旺 吴利翔[1] 林华泰 伍尚华[1] 

机构地区：[1]广东工业大学机电工程学院,广州510006

出　　处：《材料研究学报》2017年第12期894-900,共7页Chinese Journal of Materials Research

基　　金：国家自然科学基金(51674236和51034012)~~

摘　　要：研究了热压烧结的80%(体积分数,下同)B_4C/TiB_2和20%B_4C/TiB_2复相陶瓷的压痕形貌和硬度压痕的尺寸效应。与20%B_4C/TiB_2相比,80%B_4C/TiB_2具有更高的致密度和硬度,但是其断裂韧性较低。两个样品的硬度均显示出显著的硬度压痕尺寸效应(ISE),即随着载荷的增加硬度逐渐下降。但是对于80%B_4C/TiB_2样品,在载荷增加过程中出现的裂纹导致其硬度值在局部载荷范围内稍微增大。理论模拟结果表明,两个样品的ISE现象与所选定的理论模型都较为符合,其中用MPSR模型对硬度测量值的拟合最为准确,样品20%B_4C/TiB_2的ISE程度稍大于80%B_4C/TiB_2。根据理论模型,80%B_4C/TiB_2真实硬度比20%B_4C/TiB_2的高4.4~6.5 GPa。Indentation size effect on the hardness measurement of hot-pressed 80%B4C/TiB2 and 20%B4C/TiB2（in volume fraction） was investigated, while the indentation morphology was also characterized. In comparison with 20% B4C/TiB2, 80% B4C/TiB2 possesses higher relative density and hardness, but lower toughness. The two ceramics exhibit clearly the indentation size effect（ISE）, whereby the measured hardness decreases with the increasing load. However, a slight increase of the measured hardness for 80%B4C/TiB2 with the increasing load, which may be ascribed to the crack occurrence for indentations during loading.The observed ISE-phenomena for the two ceramics can be described via several existing theory models,however among them the modified proportional specimen resistance model is the most suitable one. Accordingly, the ISE-degree for 80%B4C/TiB2 ceramic is slightly stronger than that for 20%B4C/TiB2 ceramic, while the true hardness of 80%B4C/TiB2 ceramic should be 4.4-6.5 GPa higher than that of 20%B4C/TiB2 ceramic.

关 键 词：复合材料 B4C/TiB2 模拟 硬度压痕尺寸效应 显微结构 力学性能 

分 类 号：TQ174[化学工程—陶瓷工业]